Section 9 – Materials possessing chemical hazards
9.2
Hazard classification
9.2.3
Materials hazardous only
in bulk (MHB)
20 In paragraph 9.2.3, replace the existing text
under the heading with the following:
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9.2.3.1
General
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9.2.3.1.1 These are materials which possess chemical
hazards when transported in bulk other than materials classified as
packaged dangerous goods in the IMDG Code. These materials present
a significant risk when carried in bulk and require special precautions.
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9.2.3.1.2 A material shall be classified as MHB
if the material possesses one or more of the chemical hazards as defined
below. When a test method is prescribed, representative samples of
the cargo to be carried shall be used for testing. Samples shall be
taken 200 to 360 mm inward from the surface at 3 m intervals over
the length of a stockpile.
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9.2.3.1.3 A material may also be classified as
MHB by analogy with similar cargoes with known hazardous properties
or by records of accidents.
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9.2.3.2
Combustible solids
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9.2.3.2.1 These are materials which are readily
combustible or easily ignitable when transported in bulk and do not
meet the established criteria for inclusion in class 4.1 (see 9.2.2.1
of the IMSBC Code).
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9.2.3.2.2 Powdered, granular or pasty materials
shall be classified as MHB when the time of burning of one or more
of the test runs, performed in accordance with the preliminary screening
test method described in the United Nations Manual of Tests and Criteria,
part III, 33.2.1.4.3.1, is less than 2 minutes. Powders of metals
or metal alloys shall be classified as MHB when they can be ignited
and the reaction spreads over the whole length of the sample in 20
minutes or less. The test sample in the preliminary screening test
is 200 mm in length. A summary of this approach is presented in the
table below:
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Solid Cargo
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Hazard Class 4.1, PG III Burn time, Burn
distance
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MHB Burn time, Burn distance
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Powdered
Metal
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more than 5
minutes but not more than 10 minutes, 250 mm
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≤20 minutes, 200
mm
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Solid
Material
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<45 seconds,
100 mm
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≤2 minutes, 200
mm
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9.2.3.3
Self-heating solids
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9.2.3.3.1 These are materials that self-heat when
transported in bulk and do not meet the established criteria for inclusion
in class 4.2 (see 9.2.2.2).
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9.2.3.3.2 A material shall be classified as MHB
if, in the tests performed in accordance with the test method given
in the United Nations Manual of Tests and Criteria, part III, 33.3.1.6,
the temperature of the test sample rises by more than 10°C when
using a 100 mm cube sample at 140°C and at 100°C. The flow
chart below illustrates the test procedure.
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9.2.3.3.3 In addition, a material shall be classified
as MHB if a temperature rise of 10°C or more over ambient temperature
is observed during any portion of the test performed in accordance
with the test method described in United Nations Manual of Tests and
Criteria, part III, 33.4.1.4.3.5. When performing this test, the temperature
of the sample should be measured continuously over 48 hours. If, at
the end of the 48-hour period the temperature is increasing, the test
period shall be extended in accordance with the test method.
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9.2.3.4
Solids that evolve
into flammable gas when wet
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9.2.3.4.1 These are materials that emit flammable
gases when in contact with water when transported in bulk and do not
meet established criteria for inclusion in class 4.3 (see 9.2.2.3).
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9.2.3.4.2 A material shall be classified as MHB
if, in tests performed in accordance with the test method given in
the United Nations Manual of Tests and Criteria, part III, 33.4.1,
the flammable gas evolution rate is greater than zero. When performing
this test, the rate of evolution of gas shall be calculated over 48
hours at one-hour intervals. If at the end of the 48-hour period the
rate of evolution is increasing, the test period shall be extended
in accordance with the test method.
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9.2.3.5
Solids that evolve
toxic gas when wet
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9.2.3.5.1 These are materials that emit toxic
gases when in contact with water when transported in bulk.
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9.2.3.5.2 A material shall be classified as MHB
if, in tests performed in accordance with the test method given in
the United Nations Manual of Tests and Criteria, part III, 33.4.1,
the toxic gas evolution rate is greater than zero. Toxic gas evolution
shall be measured using the same test procedure for flammable gas
evolution as prescribed in the test method. When performing this test,
the rate of evolution of gas shall be calculated over 48 hours at
1-hour intervals. If at the end of the 48-hour period the rate of
evolution is increasing, the test period shall be extended in accordance
with the test method.
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9.2.3.5.3 The gas shall be collected over the
test period prescribed above. The gas shall be chemically analysed
and tested for toxicity if the gas is unknown and no acute inhalation
toxicity data is available. If the gas is known, inhalation toxicity
shall be assessed based on all information available, using testing
as a last resort option for concluding this hazard. Toxic gases in
this respect are gases showing acute inhalation toxicity (LC50)
of or below 20,000 ppmV or 20 mg/l by 4 hours' testing (GHS Acute
Toxicity Gases/Vapours Category 4).
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9.2.3.6
Toxic solids
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9.2.3.6.1 These are materials that have toxic
hazards to humans if inhaled or with contact with skin when loaded,
unloaded, or transported in bulk and do not meet the established criteria
for inclusion in class 6.1 (see 9.2.2.5).
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9.2.3.6.2 A material shall be classified as MHB
in accordance with the criteria laid down within part 3 of the GHS:
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.1 cargoes developing cargo dust with an acute
inhalation toxicity (LC50) of 1-5 mg/l by 4 hours testing
(GHS Acute Toxicity Dusts Category 4);
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.2 cargoes developing cargo dust exhibiting an
inhalation toxicity of equal to or less than 1 mg/litre/4h (GHS Specific
Target Organ Toxicity Single Exposure Inhalation Dust Category 1)
or below 0.02 mg/litre/6h/d (GHS Specific Target Organ Toxicity Repeated
Dose Inhalation Dust Category 1);
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.3 cargoes exhibiting an acute dermal toxicity
(LD50) of 1,000-2,000 mg/kg (GHS Acute Toxicity Dermal
Category 4);
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.4 cargoes exhibiting a dermal toxicity of or
below 1000 mg (GHS Specific Target Organ Toxicity Single Exposure
Dermal Category 1) or below 20 mg/kg bw/d by 90 days testing (GHS
Specific Target Organ Toxicity Repeated Dose Dermal Category 1);
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.5 cargoes exhibiting carcinogenicity (GHS Category
1A and 1B), mutagenicity (GHS Category 1A and 1B) or reprotoxicity
(GHS Category 1A and 1B).
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9.2.3.7
Corrosive solids
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9.2.3.7.1 These are materials that are corrosive
to skin, eye or to metal or are respiratory sensitizers and do not
meet the established criteria for inclusion in class 8 (see 9.2.2.7).
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9.2.3.7.2 A material shall be classified as MHB
in accordance with the criteria laid down within part 3 of the GHS:
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.1 cargoes which are known to be a respiratory
sensitizer (GHS Respiratory Sensitization Category 1);
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.2 cargoes exhibiting skin irritation with a mean
value of or higher than 2.3 for erythema/eschar or oedema (GHS Skin
Corrosion/Irritation Category 2);
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.3 cargoes exhibiting eye irritation with a mean
value of or higher than 1 for corneal opacity/irititis or 2 for conjunctival
redness/oedema (GHS Serious Eye Damage Category 1 or Eye Irritation
Category 2A).
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9.2.3.7.3 A material shall be classified as MHB
when the corrosion rate on either steel or aluminium surfaces is between
4 mm and 6.25 mm a year at a test temperature of 55°C when tested
on both materials. For the purposes of testing steel, type S235JR+CR
(1.0037 resp. St 37-2), S275J2G3+CR (1.0144 resp. St 44-3), ISO 3574:199,
Unified Numbering Systems (UNS) G10200 or SAE 1020, and for testing
aluminium, non-clad, types 7075-T6 or AZ5GU T6 shall be used. An acceptable
test is prescribed in the United Nations Manual of Tests and Criteria,
part III, section 37. When this test is performed the sample shall
contain at least 10% moisture by mass. If the representative sample
of the cargo to be shipped does not contain more than 10% moisture
by mass, water shall be added to the sample.
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